Revert "Split exception.cpp and new.cpp implementation into different files for different runtimes."

The compiler-rt CMake configuration needs some tweaking before this can land.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@294727 91177308-0d34-0410-b5e6-96231b3b80d8
17 files changed